CN-113738615-B - Vacuum pumping system with multiple positive displacement vacuum pumps and method for operating a vacuum pumping system

CN113738615BCN 113738615 BCN113738615 BCN 113738615BCN-113738615-B

Abstract

The invention relates to a vacuum pumping system with a plurality of positive displacement vacuum pumps and a method for operating a vacuum pumping system. The present invention relates to a vacuum pumping system (100) having a plurality of positive displacement vacuum pumps (20, 30) and more particularly a plurality of positive displacement vacuum pumps working in parallel, and to a method for operating such a vacuum pumping system. The vacuum pumping system (100) comprises a management unit (90) which controls all positive displacement vacuum pumps of the vacuum pumping system synchronously and thus allows to check the vacuum pumping system for possible contamination risk and, if necessary, to perform the necessary corrective actions without any need to modify the construction of the vacuum pumping system.

Inventors

Andrea bertalot
Roberto Cabury
David Lukman
PASCAL MARTIN
Christian Spada

Assignees

安捷伦科技有限公司
DH科技发展私人贸易有限公司

Dates

Publication Date: 20260512
Application Date: 20210524
Priority Date: 20200529

Claims (12)

1. A vacuum pumping system (100) having a plurality of positive displacement vacuum pumps (20, 30), the plurality of positive displacement vacuum pumps (20, 30) being connected to a same vacuum chamber (60) or to mutually communicating vacuum chambers (60, 70), respectively, the system comprising a management unit (90) for controlling the plurality of positive displacement vacuum pumps (20, 30), the plurality of positive displacement vacuum pumps (20, 30) comprising at least two positive displacement vacuum pumps connected to the same vacuum chamber (60) or to mutually communicating vacuum chambers (60, 70), respectively, the management unit (90) being configured to: -identifying one or more operating parameters of the positive-displacement vacuum pump, the one or more operating parameters being related to a risk of contamination of the vacuum pumping system by one or more of the positive-displacement vacuum pumps; -setting a threshold value or threshold state for each of said identified parameters; -detecting said identified parameters for each of said positive displacement vacuum pumps; -comparing, for each of the positive displacement pumps, the detected value or state of the identified parameter with a corresponding threshold value or threshold state; Characterized in that the management unit (90) is further configured to: -closing all of the positive-displacement vacuum pumps connected to the same vacuum chamber (60) or to the interconnected vacuum chambers (60, 70) in a synchronized manner if the detected value of one or more identified parameters of one of the positive-displacement vacuum pumps exceeds the corresponding threshold value or the detected state of one or more identified parameters of one of the positive-displacement vacuum pumps does not coincide with the corresponding threshold state.
2. The vacuum pumping system of claim 1, wherein the operating parameter is selected from the group consisting of pump frequency, power absorbed by the vacuum pump, vacuum pump absorption current, voltage absorbed by the vacuum pump, and temperature of one or more selected components of the vacuum pump.
3. The vacuum pumping system (100) of claim 1, wherein the management unit (90) is further configured to: -triggering an alarm if the detected value of the one or more identified parameters of one or more of the positive displacement pumps exceeds the corresponding threshold value or the detected state of the one or more identified parameters of one or more of the positive displacement pumps does not coincide with the corresponding threshold state.
4. A vacuum pumping system (100) as claimed in any of claims 1 to 3, wherein the management unit (90) is configured to at least one of: -detecting the identified parameter and comparing the detected value or state of the identified parameter simultaneously with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps; -detecting the identified parameter and comparing the detected value or state of the identified parameter with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps according to a predetermined sequence; -detecting the identified parameter and continuously comparing the detected value or state of the identified parameter with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps; -detecting the identified parameter and comparing the detected value or state of the identified parameter with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps at predetermined time intervals.
5. A vacuum pumping system (100) as claimed in any of claims 1 to 3, wherein the positive displacement vacuum pump is a rotary vane vacuum pump (20, 30).
6. The vacuum pumping system (100) of claim 5, wherein the rotary vane vacuum pump (20, 30) includes a housing that receives a pump body, defining a stator therein that surrounds and defines a cylindrical pumping chamber in which a cylindrical rotor is received and positioned eccentrically with respect to an axis of the pumping chamber, one or more radially movable radial vanes mounted on the rotor and held against a wall of the pumping chamber, an amount of oil being introduced into the housing to serve as a coolant and lubrication fluid, and wherein the management unit (90) is configured to: In the event that the detected value of one or more identified parameters of one of the rotary vane vacuum pumps exceeds a corresponding threshold value or the detected state of one or more identified parameters of one of the rotary vane vacuum pumps does not coincide with a corresponding threshold state, then all of the rotary vane vacuum pumps of the plurality of rotary vane vacuum pumps (20, 30) are shut down in a synchronized manner, Thereby preventing oil from the at least one rotary vane vacuum pump from being drawn through the vacuum pumping system by another of the rotary vane vacuum pumps.
7. A method of operating a vacuum pumping system (100) having a plurality of positive displacement vacuum pumps (20, 30), the plurality of positive displacement vacuum pumps (20, 30) being connected to a same vacuum chamber (60) or to mutually communicating vacuum chambers (60, 70), respectively, the plurality of positive displacement vacuum pumps (20, 30) comprising at least two positive displacement vacuum pumps connected to a same vacuum chamber (60) or to mutually communicating vacuum chambers (60, 70), respectively, the method comprising the steps of: -identifying one or more operating parameters of the positive-displacement vacuum pump, the one or more operating parameters being related to a risk of contamination of the vacuum pumping system by one or more of the positive-displacement vacuum pumps; -setting a threshold value or threshold state for each of said identified parameters; -detecting the identified parameters for each of the positive displacement vacuum pumps; -comparing, for each of the positive displacement pumps, the detected value or state of the identified parameter with a corresponding threshold value or threshold state; -closing all of the positive-displacement vacuum pumps connected to the same vacuum chamber (60) or to the interconnected vacuum chambers (60, 70) in a synchronized manner if the detected value of one or more identified parameters of one of the positive-displacement vacuum pumps exceeds the corresponding threshold value or the detected state of one or more identified parameters of one of the positive-displacement vacuum pumps does not coincide with the corresponding threshold state.
8. The method of claim 7, wherein the operating parameter is selected from the group consisting of pump frequency, power absorbed by the vacuum pump, vacuum pump absorption current, voltage absorbed by the vacuum pump, and temperature of one or more selected components of the vacuum pump.
9. The method according to claim 7, wherein the method comprises the steps of: -triggering an alarm if the detected value of the one or more identified parameters of one or more of the positive displacement pumps exceeds the corresponding threshold value or the detected state of the one or more identified parameters of one or more of the positive displacement pumps does not coincide with the corresponding threshold state.
10. The method according to any one of claims 7 to 9, wherein the method comprises at least one of the following steps: -detecting the identified parameter and comparing the detected value or state of the identified parameter simultaneously with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps; -detecting the identified parameter and comparing the detected value or state of the identified parameter with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps according to a predetermined sequence; -detecting the identified parameter and continuously comparing the detected value or state of the identified parameter with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps; -detecting the identified parameter and comparing the detected value or state of the identified parameter with corresponding threshold values or threshold states of the plurality of positive displacement vacuum pumps at predetermined time intervals.
11. The method according to any one of claims 7 to 9, wherein the positive displacement vacuum pump is a rotary vane vacuum pump (20, 30).
12. The method according to claim 11, wherein the at least one rotary vane vacuum pump (20, 30) includes a housing that receives a pump body, defining a stator therein that surrounds and defines a cylindrical pumping chamber in which a cylindrical rotor is received and positioned eccentrically with respect to an axis of the pumping chamber, one or more radially movable radial vanes mounted on the rotor and held against a wall of the pumping chamber, an amount of oil being introduced into the housing to serve as a coolant and lubrication fluid, and wherein the method includes the steps of: Turning off all of the rotary vane vacuum pumps (20, 30) of the plurality of rotary vane vacuum pumps in a synchronized manner if the detected value of the one or more identified parameters of one of the rotary vane vacuum pumps exceeds the corresponding threshold value or the detected state of the one or more identified parameters of one of the rotary vane vacuum pumps does not coincide with the corresponding threshold state, Thereby preventing oil from the at least one rotary vane vacuum pump from being drawn through the vacuum pumping system by another of the rotary vane vacuum pumps.

Description

Vacuum pumping system with multiple positive displacement vacuum pumps and method for operating a vacuum pumping system Technical Field The present invention relates to a vacuum pumping system having a plurality of positive displacement vacuum pumps, and more particularly a plurality of positive displacement vacuum pumps operating in parallel. The invention also relates to a method for operating a vacuum pumping system having a plurality of positive-displacement vacuum pumps, and more particularly a plurality of positive-displacement vacuum pumps working in parallel and/or connected to vacuum chambers communicating with each other. Background The vacuum pump is used to achieve a vacuum state, i.e. to evacuate a chamber (a so-called "vacuum chamber") and to establish a sub-atmospheric pressure state in said chamber. Many different types of vacuum pumps are known, having different constructions and operating principles, and each time a particular vacuum pump is selected according to the needs of a particular application, i.e. according to the vacuum level to be achieved in the respective vacuum chamber. Positive displacement vacuum pumps displace gas from a sealed region to the atmosphere or downstream pumping stages. Positive displacement pumps are very efficient and cost effective in creating a low vacuum condition. For this reason, it may be used as the primary pump in a vacuum system, but it is often used as a pressure pump for other pumps, such as turbomolecular pumps. Unfortunately, in some cases, positive displacement vacuum pumps, such as rotary vane pumps or scroll pumps, may contaminate the vacuum system in which they are installed. Rotary vane vacuum pumps may be considered by way of non-limiting example. Fig. 1 and 2 schematically illustrate a vacuum pumping apparatus 150 comprising a conventional rotary vane vacuum pump 110 and an associated motor 140. As shown in fig. 1 and 2, a conventional rotary vane vacuum pump 110 generally includes a housing 112 that receives a pump body 114, with a stator defined within the pump body 114 that surrounds and defines a cylindrical pumping chamber 116. The pumping chamber 116 houses a cylindrical rotor 118, the rotor 118 being positioned eccentrically with respect to the axis of the pumping chamber 116, one or more radially movable radial vanes 120 (two in the example shown in fig. 2) being mounted on said rotor 118 and held against the wall of the pumping chamber 116, for example by springs 122. During operation of the vacuum pump 110, gas flows from the vacuum chamber through the inlet port 124 of the pump and is transferred through the suction line 126 into the pumping chamber 116, which is pushed by the vanes 120 at the pumping chamber 116 and thus compressed, and which is then discharged through the discharge line 128 ending at the corresponding outlet port 130. An appropriate amount of oil is introduced into the housing 112 from an oil tank (not shown) to serve as a coolant and a lubricating fluid. In the example shown in fig. 2, for example, the inner housing 114 is submerged in the oil sump 132. To drive the rotor 118 of the vacuum pump, the vacuum pumping apparatus 150 further includes a motor 140, and the pump rotor 118 is mounted to a rotation shaft driven by the motor. As described above, in the rotary vane vacuum pump, oil is used to lubricate and cool the moving parts of the pump. In this type of pump, the oil also acts as a sealant for providing a seal between the areas at different pressures. There is a risk of oil vapor inducing backflow at the inlet of the vacuum pump and contaminating the vacuum chamber being evacuated by the vacuum pump. This risk is even higher in vacuum pumping systems where there are two or more rotary vane vacuum pumps working in parallel and/or connected to vacuum chambers communicating with each other. Indeed, in such a complex vacuum pumping system, if one of the rotary vane vacuum pumps is stopped due to a failure, the other rotary vane vacuum pump of the vacuum pumping system may suck oil vapor at the inlet of the vacuum pump that has been stopped. The sucked oil is thus transferred through the vacuum chamber to which the vacuum pump is connected, and the final effect is to contaminate the vacuum pumping system. In order to prevent contamination of the vacuum chamber, positive displacement vacuum pumps, such as rotary vane vacuum pumps, may be equipped with protection means to avoid pressure rise and/or oil backflow towards the vacuum chamber when the pump is turned off. In this way, the vacuum chamber can be completely isolated from the positive displacement vacuum pump. In the case of a vacuum pumping system with multiple positive displacement vacuum pumps working in parallel, each positive displacement vacuum pump is equipped with its own protection device, such as a backflow prevention valve, which prevents backflow towards the vacuum chamber, thus inhibiting the risk of contamination of the vacuum chamber. Ho